A typical turbine rotor assembly of a gas turbine engine has a plurality of turbine blades or airfoils extending radially outward from a central disk across a fluid path. Turbine blades generally comprise a unitary casting consisting of an airfoil section formed radially outward of a platform, which is formed radially outward of a blade root section. The blade is mounted to the disk by sliding the root portion of the blade into a mating slot cut in the disk. High pressure, high temperature combustion products from the combustion section flow past the plurality of airfoils, which in turn, convert a portion of the thermodynamic energy in the fluid into mechanical energy in the form of a torque about the engine shaft, which causes the shaft to turn at a high rate of speed.
The high rotational speeds typical in a modem gas turbine engine produce high centripetal acceleration and correspondingly high stresses in the turbine disk and blade root. Because the major stress component is acceleration induced, simply adding additional material in high stress areas often does not result in an improved design, since the additional material also adds additional mass to the rotating system. Accordingly, what is needed is a feature in the blade and disk that minimizes peak stress without adding significant mass to the rotating system.